Gardening for Pollinators

WHEN I FIRST STARTED TO GARDEN FOR WILDLIFE at my home in central Pennsylvania, I was thinking about birds. I planted native trees and fruiting shrubs for the local wrens and towhees, which love the nest sites, berries and caterpillars that native plants support. But as every gardener knows, a garden is never done! This spring I’m planting for pollinators.

At first I just wanted to help native bees. Many of North America’s more than 4,000 species are declining, including more than a quarter of native bumble bees such as the western bumble bee and the rusty patched bumble bee. But creating pollinator habitat doesn’t just help the bees; it also helps your fruits and vegetables.

Common crops that benefit from healthy populations of pollinators include apples, cherries, blueberries, tomatoes, eggplants, peppers and pumpkins. “It’s a win for wildlife and for gardeners: bigger produce and more square footage for habitat,” says Mary Phillips, director of the National Wildlife Federation’s Garden for Wildlife™ program.

Miniature Crop Dusters

All bees visit flowers for nectar and nutritious pollen. In the process, bees move pollen from anthers (male flower parts) to ovaries (female parts), helping flowers set seed and make fruit. But native bees are more effective pollinators than nonnative honey bees, and body structure plays a role. Where honey bees pack pollen into tidy baskets on their legs, most native bees are like little flying dust mops: Pollen clings to hairs on their bodies and easily brushes off, so flowers get pollinated more completely.

Behavior can also play a role. Native blue orchard bees are more willing to fly when it’s cold and damp. And whereas honey bees will visit a single fruit tree methodically going from flower to flower, orchard bees flit from tree to tree, resulting in the cross-pollination some trees need to set fruit. Bumble bees also do a nifty trick honey bees don’t called “buzz pollination”: They vibrate their flight muscles at the exact frequency needed to shake pollen loose from anthers.

Blueberries are one crop that benefits. When researchers at Michigan State University planted wildflowers around high-bush blueberry fields to attract native pollinators, they saw the wild bee population double within two years and blueberry yields increase up to 20 percent.

Claire Kremen, a researcher at the University of California­–Berkeley who studies how creating habitat for native pollinators helps farm crops, notes that tomatoes don’t need bees because they can self-pollinate. “But when tomatoes get regular visits from buzz pollinators,” she says, “they make more and bigger tomatoes—up to a 50 percent increase in yield and tomatoes twice as big.”

Kremen’s research shows that strips of wildflowers interspersed with farm fields are especially effective at increasing populations of native pollinators. This approach “totally translates to the backyard,” she says. In her yard, she places native flowering shrubs from California’s chaparral ecosystem (such as California lilac and coffeeberry) around the edge of her yard with her veggie garden in the middle.

For your garden, choose locally native perennials of yellow, blue or purple, the colors most attractive to bees. Variety is also important. “Different pollinators are active at different times in the growing season,” Kremen says. “A variety of bees will do a better job pollinating your garden than one species alone. If you grow different flowers, there’s always something blooming to attract them.”

Tips to Lure Pollinators

Don’t have room for new flowerbeds? Judy Seaborn, co-founder of the organic seed company Botanical Interests, plants herbs like basil and cilantro in her vegetable beds, then lets some of the herbs flower for the bees. “Thyme, oregano and borage flowers also attract pollinators,” she says.

Bees drink water as well as nectar, so Seaborn created a water feature for them—a large flat stone with a shallow basin. “When I water the garden, I make sure to splash the stone to fill the basin. Bees really like it,” she says.

Mace Vaughan gardens for pollinators even though he lives on a shady lot in rainy Portland, Oregon. The co-director of the Xerces Society for Invertebrate Conservation’s Pollinator Program did some research to identify shade-tolerant, flowering native plants and left patches of soil exposed under hedges to attract ground-nesting bees. “Now tons of bees visit,” he says, to the benefit of his raspberries and blueberries.

Beyond benefiting bees and your garden, native bees are fun to watch —and these visitors change with the seasons. You’ll see metallic green mason bees or furry little mining bees in spring, squash bees darting after mates in midsummer and long-horned bees in late summer, with antennae that make them look like tiny antelopes. I’m looking forward to seeing more of this menagerie in my own garden when I plant for pollinators. Why don’t you join me? You’ve got nothing to lose . . . and bigger, better cherry tomatoes to gain.

Longtime contributor Cynthia Berger wrote about urban wildlife in the February-March 2015 issue.